Patent EA-002889-B1 (EA)
Title: Electronic trip device with phase reconstitution and a circuit breaker comprising such a trip device
Inventor: BOUDAUD DOMINIQUE
IPC: H02H3/08
Filed: 2000-04-13
Abstract: 1. A trip device with phase reconstitution comprising: - at least two sensors (2, 3) arranged on main conductors (36) to be protected, and - a processing unit (1) comprising means (4) for processing the current signals connected to the sensors, means (6) for phase reconstitution receiving signals (Isl, Is3) representative of the current signals supplied by the sensors, and means (5) for processing tripping functions connected to the means for processing the current signals and to the means for reconstitution, trip device characterized in that the means for phase reconstitution comprise: - first determining means (11, 12, 25) to determine signals (Ial, Ia3) representative of the amplitudes of the current signals (Isl, Is3) supplied by the two sensors, - second determining means (15, 27-33) to determine a signal (F(φ), S(φ), cos(φ), (φ), (φ0) representative of a phase shift between signals representative of the signals (Isl, Is3) supplied by the two sensors, and - third determining means (13, 14, 16, 17, 34) connected to the first and second determining means to determine a signal (Ia2<2>, Ia2,12) representative of a phase current reconstituted according to the signals representative of the amplitudes and to the signal representative of a phase shift of the signals supplied by the two sensors. 2. The trip device according to Claim 1, characterized in that the second determining means comprise means (15, 33) for computing the cosine of the phase shift between the signals representative of the signals (Isl, Is3) supplied by the two sensors. 3. The trip device according to one of the Claims 1 or 2, characterized in that the second determining means comprise means for determining times when the signals supplied by the current sensors pass zero in a predetermined direction, said times being a first time (tl) when a first signal (Isl) passes zero, a second time (t2) when a second signal (Is3) passes zero and a third time (t3) when a first signal (Isl) again passes zero, a signal representative of the phase shift being appreciably proportional to the ratio of a time (t2-tl) between the first (tl) and second (t2) times over a time (t3-tl) between the first (tl) and third (t3) times corresponding to the period of the first signal. 4. The trip device according to any one of the Claims 1 to 3, characterized in that the third determining means comprise first means (16) for computing a product signal (P) to calculate the product of the signals representative of the amplitudes and of the signal representative of a phase shift. 5. The trip device according to Claim 4, characterized in that the third determining means comprise second means (17) for computing a sum signal (Ia2<2>) to calculate the sum of the squared amplitude signals (la I<2>, Ia3<2>) and of the product signal (P). 6. The trip device according to any one of the Claims 1 to 5, characterized in that it comprises means (20) for determining zero-phase sequence current comprising a current sensor (21) arranged on all of the main conductors. 7. The trip device according to any one of the Claims 1 to 6, characterized in that the means for reconstitution use the signal supplied by the third determining means when at least one of the current signals (Isl, Is3) supplied by the two sensors exceeds a first preset threshold (S1). 8. The trip device according to any one of the Claims 1 to 7, characterized in that each current sensor (2, 3) surrounds two main conductors. 9. The trip device according to any one of the Claims 1 to 8, characterized in that it comprises at least three sensors (2, 3, 37) arranged on main conductors (36) to be protected, the first determining means (11, 12, 25) determining signals (lal, Ia3) representative of the amplitudes of the current signals (Isl, Is3) supplied by the sensors, and the third determining means (13, 14, 16, 17, 34) connected to the first and second determining means determining a signal (Ia2<2>, Ia2,12) representative of a phase current reconstituted according to the signals representative of the amplitudes (Ial, Ia3), to the signal representative of a phase shift (φ,φ0) of the signals supplied by two sensors (2, 3), and to a signal (Isn) supplied by a third sensor (36). 10. A circuit breaker comprising at least three contacts (8) connected in series with main conductors (36) characterized in that it comprises a trip device according to any one of the Claims 1 to 9.